1. Inheritance in Java is a mechanism in which one object acquires all the properties
and behaviors of a parent object. It is an important part of OOPs.
The idea behind inheritance in Java is that you can create new classes that are built
upon existing classes. When you inherit from an existing class, you can reuse
methods and fields of the parent class.
Why use inheritance in java
o For Method Overriding
(so runtime polymorphism can be achieved).
o For Code Reusability.
Terms used in Inheritance
o Class: A class is a group of objects which have common properties. It is a
template or blueprint from which objects are created.
o Sub Class/Child Class: Subclass is a class which inherits the other class. It is
also called a derived class, extended class, or child class.
o Super Class/Parent Class: Superclass is the class from where a subclass
inherits the features. It is also called a base class or a parent class.
o Reusability: As the name specifies, reusability is a mechanism which facilitates
you to reuse the fields and methods of the existing class when you create a
new class.
2. The syntax of Java Inheritance
class Subclass-name extends Superclass-name
{
//methods and fields
}
The extends keyword indicates that you are making a new class that derives from an
existing class. The meaning of "extends" is to increase the functionality.
Java Inheritance Example
class Employee
{
float salary=40000;
}
class Programmer extends Employee
{
int bonus=10000;
3. }
public static void main(String args[])
{
{
Programmer p=new Programmer();
System.out.println("Programmer salary is:"+p.salary);
System.out.println("Bonus of Programmer is:"+p.bonus);
}
}
Types of inheritance in java
On the basis of class, there can be three types of inheritance in java: single, multilevel
and hierarchical.
In java programming, multiple and hybrid inheritance is supported through interface
only. We will learn about interfaces later.
4. Single Inheritance Example
When a class inherits another class, it is known as a single inheritance.
Single Inheritance Example
When a class inherits another class, it is known as a single inheritance.
5. Single Inheritance Example
When a class inherits another class, it is known as a single inheritance.
class Animal
{
void eat()
{
System.out.println("eating...");
}
}
class Dog extends Animal
{
void bark()
{
System.out.println("barking...");
}
}
class TestInheritance
{
public static void main(String args[])
{
Dog d=new Dog();
d.bark();
d.eat();
}
}
barking...
eating...
6. Multilevel Inheritance Example
When there is a chain of inheritance, it is known
{
void eat()
as multilevel inheritance.
class Animal
{
System.out.println("eating...");
}
}
class Dog extends Animal
{
void bark()
{
System.out.println("barking...");
}
}
class BabyDog extends Dog
{
void weep()
{
System.out.println("weeping...");
}
}
class TestInheritance2
{
public static void main(String args[])
{
BabyDog d=new BabyDog();
d.weep();
d.bark();
7. d.eat();
}
}
Output:
weeping...
barking...
eating...
Hierarchical Inheritance Example
When two or more classes inherits a single class, it is known as hierarchical
inheritance.
class Animal
{
void eat()
{
System.out.println("eating...");}
}
class Dog extends Animal
{
void bark()
{
System.out.println("barking...");}
}
class Cat extends Animal
{
void meow()
{
System.out.println("meowing...");}
}
class TestInheritance3
{
public static void main(String args[])
{
Cat c=new Cat();
c.meow();
